The present invention relates to valve assemblies and, in particular, to an electronic valve block assembly for controlling the operation of glassware forming machinery.
Glassware forming machines typically comprise a plurality of individual sections (IS) cooperating to receive, in ordered sequence, gobs of molten glass from a single source. Each individual section (IS) of the glassware forming machine itself includes a plurality of pneumatically operated elements. The relative operating sequence of the respective elements of each IS machine is controlled through selective actuation of an associated valve typically disposed in a valve block. There are typically 19 or 21 separate valves utilized in the control of the complete glassware forming sequence.
The actuation of the valves in the block has typically been effected by a mechanical timing drum driven in synchronism with the gob feeding mechanism. Respective projecting cam members are disposed in annular grooves in the drum surface and mechanically cooperate with the valves to effect activation and deactivation. Relative timing between events in the machine cycle are adjusted by the relative position of the respective cam members in the annular grooves. For a basic description of such a glassware forming machine, reference is made to U.S. Pat. No. 1,911,119 issued May 23, 1933 to H. W. Ingle.
Electronic sequencing of the respective elements of the glassware forming machine is now emerging. For a description of electronically controlled glassware forming machinery, reference is made to U.S. Pat. No. 3,762,907 issued Oct. 2, 1973 to Quinn and Kwaitkowski and U.S. Pat. No. Re 29,642, reissued May 23, 1978 to Kwaitkowski and Wood (both commonly assigned with the present application). Briefly, in electronically controlled glassware forming machines, actuation signals are generated by an electronic controller to selectively actuate or deactivate solenoid operated valves, or the like, to effect timed operation of the respective glassware forming machine elements. The actuation signals are generated in synchronism with the machine cycle as defined by the molten glass gob feeder.
Typical solenoid controlled valve blocks are described in U.S. Pat. No. 3,918,489 issued Nov. 11, 1975 to Foster et al and U.S. Pat. No. 3,982,726 issued Sept. 28, 1976 to Bublitz et al. It is noted that in electronic valve blocks, the space required by the valves within the valve block must be minimized in order to incorporate all of the 19 or more pneumatic valves into the valve block.
In addition, the compactness requisites for the valve block are magnified by a need for plural air pressures for operation of the IS machine in various modes. Conventional electronic valve blocks have required external plumbing to provide the various air pressures as required. Accordingly, when the machine is converted for production of different types of bottles, (i.e., job change) replumbing of the machine is often required. Job changes on IS machines can occur as frequently as on a less than weekly basis. As can readily be appreciated, the replumbing of the machine can be very costly in terms of production downtime.
Mitigating against the need for compact valves is the necessity of ample air flow to maintain the operational speeds of the IS elements. Also, mitigating against compact valves is the desirability to be able to operate the IS machine functions with unfiltered air. In the typical operation of the IS machine, various condensations, cylinder oil, sludge and varnish from the compressor, and the like, tend to find its way into the air lines. The foreign materials often play havoc with close tolerance orifices in the valves. As can readily be appreciated, installation of additional filtering apparatus, and frequent cleaning or change of the filters entails substantial costs.
Similarly, it is often desirable to have vacuum (reverse pressure) available for various machine functions. For example, a vacuum is often utilized to "assist" in settling a gob of molten glass in the finish portion (threaded portion or neck) of a mold during the formation process. Vacuum is generally provided through massive hard-plumbed piping, and manifolds located under the IS machine in the so-called "bed level".
In general, two-tiers of valves are utilized to provide control of application of vacuum. Solenoid operated pilot valves, under the auspices of the controller, selectively provide pilot air to pilot operated spring return power valves generally located in the bed level piping under the machine. The power valves, in turn, provide "blank-side" vacuum to the bottle finish area. Thus, vacuum is only indirectly controlled by the solenoid valves.
The two-tiered control system and disposition of the vacuum lines and power valves in the bed level cause serious problems in providing controlled vacuum assist to the IS. The environment in the bed level of the IS machine is particularly harsh, causing frequent failure of the power valves. Moreover, the power valves in the bed level are relatively inaccessible.
A still more serious problem arises from the delay time and inconsistent operation inherent in the two-tier system due to the relatively long lengths of piping used. The disposition of the vacuum line and power valve in the bed level necessitates piping from the bed level to the blank-side bottle finish apparatus. The piping between the finish apparatus must be evacuated before vacuum is established in the finish area. Thus, a delay, which varies depending on the amount of time required to evacuate the piping is interjected into the system. The time required to evacuate the piping often in itself, varies due to power fluctuations, foreign matter in the lines, or other substantially uncontrollable factors. An additional delay is entailed in supplying the pilot air from the solenoid valve to the power valve.
It should be appreciated that accurate timing of the vacuum to the finish area of the bottle is critical to the effectiveness of the vacuum assist.
An additional problem has arisen with the conventional electronic valve block in that the malfunction of a single valve can often necessitate the removal of the entire valve block to effect repairs requiring the IS machine to shut down for lengthy periods.
In addition, the conventional electronic valve block provides the actuating air at output ports which must mate with a manifold (kissplate) to the glassware forming machine. However, the spatial configuration of the manifold inputs vary on the various types and models of glassware forming machines. Accordingly, special plumbing must be provided to couple the output ports of the conventional electronic valve block to the manifold of different IS machines.